The red hot mess of the Cura settings screen is a raging disaster to sort through. Documentation of how to use various features is poorly documented, at best. I mean, unless you are a devout follower on the Ultimaker board or here, so many of these features are unknown.

Cura does very well on the Ultimaker with the built in profiles and such. But on trickier prints that involve generating and moving supports as I need them, S3D still wins.

Performance wise....again, Cura runs awful slow on my new Intel i5 laptop and bogs down on my Intel i7 with a fast SSD drive and 32gb of RAM.

I keep trying to stay up to date with what Cura can do on each version. But I'm not convinced it's better. Not yet anyways

I have filed a bug on Cura 3.0.4 crashing. For me, it was when I was editing the color of my Aua Glow filament in the Materials Manager. Just that one filament seems to blow up when I try to change from default yellow to light blue. Very odd. Works in 2.7, so I consider this a regression.